The present invention relates to latches and latching methods, and more particularly to devices and methods for electronically controlling and switching a latch between latched and unlatched states.
Conventional latches are used to restrain the movement of one member or element with respect to another. For example, conventional door latches restrain the movement of a door with respect to a surrounding door frame. The function of such latches is to hold the door secure within the frame until the latch is released and the door is free to open. Existing latches typically have mechanical connections linking the latch to actuation elements such as handles which can be actuated by a user to release the latch. Movement of the actuation elements is transferred through the mechanical connections and will cause the latch to release. The mechanical connections can be one or more rods, cables, or other suitable elements or devices. Although the following discussion is with reference to door latches (e.g., especially for vehicle doors), the background information provided applies equally to a wide variety of latches used in other applications.
Most current vehicle door latches contain a restraint mechanism for preventing the release of the latch without proper authorization. When in a locked state, the restraint mechanism blocks or impedes the mechanical connection between the handle and a latch release mechanism, thereby locking the door. Many conventional door latches also have two or more lock states, such as unlocked, locked, child locked, and dead locked states. Inputs to the latch for controlling the lock states of the latch can be mechanical, electrical, or parallel mechanical and electrical inputs. For example, by the turn of a user""s key, a cylinder lock can mechanically move the restraint mechanism, thereby unlocking the latch. As another example, cable or rod elements connecting a door handle to the latch release mechanism can be controlled by one or more electrical power actuators. These actuators, sometimes called xe2x80x9cpower locksxe2x80x9d can use electrical motors or solenoids as the force generator to change between locked and unlocked states.
A number of problems exist, however, in the conventional door latches described above. For example, conventional restraint mechanisms in such latches are typically quite complex, with numerous parts often having relatively complicated movements. Such latches are thus more expensive to manufacture, maintain, and repair. This problem is compounded in latches having multiple lock states as mentioned above. These latches often require separate sets of elements corresponding to and controlling each lock state of the latch. Related to this problem are the problems of latch weight and size. The inclusion of more elements and more complex mechanisms within the latch generally undesirably increases the size and weight of the latch. In virtually all vehicle applications, weight and size of any component is a concern. Additionally, increased weight and size of elements and assemblies within the latch necessarily requires more power and greater force to operate the latch. Because power is also at a premium in many applications (especially in vehicular applications), numerous elements and complex assemblies within conventional door latches are an inefficiency that is often wrongly ignored. Not only are larger and more complex latches a power drain, but such latches are typically unnecessarily slow.
Another problem with conventional door latches relates to their operation. Particularly where a latch has multiple lock states, the ability of a user to easily and fully control the latch in its various lock states is quite limited. For example, many latches having a child locked state (i.e., the inside door handle is disabled but the outside door handle is not) require a user to manually set the child locked state by manipulating a lever or other device on the latch. Other latches do not permit the door to enter a dead locked state (i.e., both the inside and outside door handles being disabled). Also, conventional door latches generally do not permit a user to place the door latch in all lock states remotely, such as by a button or buttons on a key fob. These examples are only some of the shortcomings in existing door latch operability.
Still another problem of conventional door latches is related to power locks. The design of existing power lock systems has until now significantly limited the safety of the latch. Latch design limitations exist in conventional latches to ensure, for example, that dead locked latches operated by powered devices or systems will reliably unlock in the event of power interruption or failure. Such limitations have resulted in latch designs which permit less than optimal user operability. Therefore, a reliable design having a failure mode for an electrically powered latch which is electrically actuatable in all locked states remains an elusive goal.
In conventional door latches, yet another problem is caused by the fact that an unauthorized user can often manipulate the restraint mechanism within the latch and/or the connections of the latch to the door locks to unlock the latch. Because existing conventional door latches have at least some type of mechanical linkage from the user-actuated elements (e.g., lock cylinders) to the restraint mechanism in the latch, the ability of an unauthorized user to unlock the latch as just described has been a persistent problem.
In light of the problems and limitations of the prior art described above, a need exists for a latch assembly which has the fewest elements and assemblies possible, is smaller, faster, and lighter than existing latches, consumes less power in operation, is less expensive to manufacture, maintain, and repair, provides a high degree of flexibility in user operation to control the lock states of the latch, has a reliable design in the event of power interruption or failure, and offers improved security against unlocking by an unauthorized user. Each preferred embodiment of the present invention achieves one or more of these results
In the most highly preferred embodiments of the latch assembly of the present invention, unlocked and locked states of the latch assembly are established by at least two different types of movement of a control element. The control element moves in a first manner through a first path when the latch assembly is in an unlocked state and in a second manner through a second path when the latch assembly is in a locked state. When the control element moves in the first manner, the control element imparts motion either directly or indirectly to a latch element or mechanism (e.g., a ratchet). Such motion moves the latch element or mechanism to move to its unlatched position to unlatch the door. In contrast, when the control element moves in a second manner, the control element does not impart motion (or sufficient motion) to the latch element or mechanism for unlatching the door. Therefore, whether movement or actuation of the control element by a user will unlatch the latch depends upon whether the control element moves in the first or the second manner. The latch assembly of the present invention operates to quickly change the manner of control element motion by preferably extending or retracting one or more elements that guide or limit the motion of the control element. Preferably, these elements are pins which are quickly extended and retracted by one or more actuators.
A highly preferred embodiment of the present invention has two control elements, pins, and actuators. In each control element, pin, and actuator set, the actuator can be extended to extend the pin into a hole in the control element and can also be retracted to retract the pin from the hole. When the actuator and pin are extended and thereby engage the control element, the control element preferably pivots through a first path about a first pivot point. However, when the actuator and pin are retracted and are thereby disengaged from the control element, the control element preferably pivots through a second path about a second pivot point. Movement of the control element through the first path preferably brings the control element into contact with a pawl that is coupled to the latch element or mechanism. This contact causes the latch element or mechanism to release, thereby unlatching the door. In contrast, movement of the control element through the second path preferably does not bring the control element into such contact, or at least into contact sufficient to release the latch element or mechanism. The control element in the second path therefore is in a locked state.
In the most highly preferred embodiments of the present invention, the actuators are electro-mechanical solenoids that perform quick retraction and extension operations to engage and disengage the control elements in their different lock states. The control elements preferably pivot about a hole in each control element that is engaged by the pin in the extended position and about a post, peg, or other element extending from each control element when the pin is not engaged therewith.
In referring herein to xe2x80x9cretractionxe2x80x9d and xe2x80x9cextensionxe2x80x9d operations of solenoids and to xe2x80x9cretractedxe2x80x9d and xe2x80x9cextendedxe2x80x9d positions of the solenoids, it should be understood that this is with reference to well known operation of conventional solenoids. Specifically, solenoids typically have one or more elements (such as an armature) which are controllable to extend and retract from the remainder of the solenoid in a well known manner. Terms such as retraction, retracted, extension and extended used herein in connection with a solenoid refers to such conventional solenoid operations.
When the latch assembly of the present invention is used on a vehicle door, a first control element is coupled via a linking member to an inside door handle and a second control element is preferably coupled to an outside door handle. When the pin corresponding to each control element is extended to engage the first and second control elements, respectively, actuation of the control elements by either handle causes the actuated control element to directly or indirectly move a ratchet to unlatch the door. This is the unlocked state of the latch assembly. When the pin corresponding to each control element is retracted to disengage the first and second control elements, actuation of the control elements by either handle does not move the ratchet or does so insufficiently to unlatch the door. This is the dead locked state of the latch assembly. When the pin corresponding to the first control element is extended to engage the first control element and when the pin corresponding to the second control element is retracted to disengage the second control element, actuation of the inside door handle will directly or indirectly move a ratchet to unlatch the door, but actuation of the outside door handle will not do so. This is the locked state of the latch assembly. When the pin corresponding to the first control element is retracted to disengage the first control element and the pin corresponding to the second control element is extended to engage the second control element, actuation of the outside door handle will move the pawl and unlatch the door, but actuation of the inside door handle will not do so. This is the child locked state of the latch assembly. Of course, in other embodiments of the present invention, one, three, or even more control element, pin, and actuator sets can be used as desired.
Latch assembly operations for placing the control elements in their locked and unlocked states are therefore quickly performed via actuators, and most preferably, by electro-magnetic solenoids. Also, the relatively small number of elements (e.g., an actuator, pin, control element, and, if desired, a pawl as described in more detail below) employed to place the latch assembly in its various lock states is a significant advantage over prior art latches. The latch assembly of the present invention is therefore lighter, smaller, can be operated using less power, and can be manufactured, maintained, and repaired at less expense.
In addition, the use of electrical actuators such as electromagnetic solenoids to place the control elements in their various states permits greater flexibility for users in controlling the various latch assembly lock states.
The latch assembly of the present invention also preferably has a control circuit for controlling the actuators. Most preferably, the control circuit is electrical and uses a sensing device to detect changes in the primary power supply (e.g., power loss, power interruption, etc.) supplying power to the latch assembly and to the actuators. At least as a safety feature, certain changes detected in the power supply preferably cause the actuators to automatically engage the pins with the control elements and to thereby unlock the latch assembly.
Because the mechanism for placing the latch assembly in its various lock states is preferably actuated electronically rather than by conventional mechanical means, the latch assembly is also more secure against unauthorized operation. More information and a better understanding of the present invention can be achieved by reference to the following drawings and detailed description.